No Spark

Your coil does not need an external ground.

If the polarity is reversed at the butt connectors, you will need to hunt for the initial timing, AND, the engine will not take much throttle before crapping out. A check of the timing will reveal it to be jumping all over the place.

By this time, I wonder if she's flooded.

If your MSD is currently your amp, it requires the ignition and start wires to be jumped together to provide a continuous signal to the amp. This cannot be so wired on the factory ignition switch, as the starter solenoid will receive a continuous battery voltage, and pulling it through the ignition switch. If it can pull hard enough it will try to crank the engine every time you put it in Park or Neutral.The proper solution is to use a small isolation relay. I think the MSD instructions detail this procedure.